In the cooking of food and preparation of hot beverages, it is possible to produce satisfactory results for many dishes without ever raising the internal temperature of the food or beverage above the range of 75-85.degree. C. If this upper limit is accepted, it becomes practical to consider heating food or beverages in quantities of 1/4 to 1 liter using relatively low power electrical energy: vis 40 to 100 Watts. With these limiting conditions, it is feasible to use batteries and solar panels as the electrical energy source.
Most, if not all, consumer product heater elements are fabricated from a conductor, usually thermal wire or possibly carbon, embedded in an insulating material, usually a ceramic. Most heating elements paths are in the form of a strip, multi-ring spiral, or multi-leg parallels. They are generally highly rigid and are supported at specific locations on metal posts. There is not generally available on the market a heater element composed of a uniform partially conducting material that is supported over the greater part of its underside surface.
To make most efficient use of electrical energy from low power sources, it is important to design the electrical heating element in a form that is low cost, robust, and energy efficient. This invention addresses these objectives.
Amongst the main challenges of the invention are to:
configure a device that operates at a low enough temperature to not damage the element or base materials; PA1 avoid the development of "hot spots" on the surface of the element; PA1 effect a low resistance electrical contact to the preferred element material that will permit high currents to be employed. PA1 allow a relatively uniform current density and resulting uniform heat dissipation, PA1 allow an available resistivity for the material and applications intended, PA1 maximize the surface area and thereby to minimize the operating temperature over the surface area, PA1 provide adequate structural rigidity to provide a robust element, PA1 allow the interruption of the path for the electrical connection to be done at any convenient point in the path.
The invention in its general form will first be described, and then its implementation in terms of specific embodiments will be detailed with reference to the drawings following hereafter. These embodiments are intended to demonstrate the principle of the invention, and the manner of its implementation. The invention in its broadest and more specific forms will then be further described, and defined, in each of the individual claims which conclude this specification.